The phrase "which is mentioned" is correct and usable in written English.
You can use it when referring to something specific that has been mentioned previously. For example: "He mentioned his brother's party, which is mentioned in the article."
Refugees note that Muslims first bowed in prayer toward Al Aksa mosque, which is mentioned in the Koran.
The village, which is mentioned in the Doomsday Book under the name Chauescote, has a population of 706.
The title is taken from Lady Antebellum's country song American Honey, which is mentioned at the beginning and sung by the crew at the end.
It sounds as if the note, which is mentioned in a big article in Vanity Fair, was written (assuming it was written) after the right hook.
My mother-in-law is the one who found that dead body behind the Italian restaurant that she owned on St. Mark's (which is mentioned in the book).
Ron Padgett is a crucial nexus in the publication and teaching of poetry and a central figure in the New York School (which is mentioned in "Paterson").
Willmore said that she had been looking for "The Doll", which is mentioned in Du Maurier's autobiography, Myself When Young, for many years.
Frank O'Hara's World and Ours Have students read the Frank O'Hara poem "The Day Lady Died," which is mentioned in the article.
The replacement of the bells, which is mentioned without fanfare on a placard inside the church, has caused a small but very Parisian ruckus.
Though czarist prisons would seem mild compared with those Stalin would establish, they had their horrors, one of which is mentioned in nearly all prison memoirs of the time — listening as your comrades are taken out to be hanged.
Lod, which is mentioned in the Bible, was an important center in ancient times, and this part of it is known to have been a neighborhood of the rich.
